Chromium-free welding consumable

ABSTRACT

A chromium-free welding consumable and a method of welding stainless steel to reduce the presence of chromium emissions. The consumable is made from an alloy that reduces the emission of chromium during a welding process, and include predominantly nickel, with between approximately five and twenty five percent by weight copper, up to approximately five percent by weight of palladium, up to approximately ten percent by weight of molybdenum and up to five percent non-copper alloying ingredients. Welding consumables made from the alloy are particularly well-suited for welding austenitic stainless steels, such as type 304 stainless steel. The method involves using chromium-free weld filler material with a stainless steel base material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S.Provisional Application No. 60/557,031, filed Mar. 26, 2004.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was supported by the government under Contract No. DACA72-03-P-0014 awarded by the Department of Defense under the StrategicEnvironmental Research and Development Program. The government hascertain rights in the invention.

BACKGROUND OF THE INVENTION

This invention relates generally to chromium-free welding materials, andin particular to a chromium-free welding consumable and methodsemploying such consumables for joining or repairing stainless steel basemetals, where the weld retains its structural and corrosion properties,even in harsh environments.

Stainless steels or, more precisely, corrosion-resisting steels are afamily of iron-base alloys having excellent resistance to corrosion.These steels do not rust and strongly resist attack by a great manyliquids, gases, and chemicals. Stainless steels are generally dividedinto three classes, austenitic, ferritic or martensitic (with a possibleaustenitic-ferritic duplex class), depending on the predominantmicrostructural phase. Many of the stainless steels have goodlow-temperature toughness and ductility, and generally exhibit goodstrength properties and resistance to scaling at high temperatures. Allstainless steels contain iron as the main element and chromium (Cr) inamounts ranging from about 11% to 30%, where the presence of chromium insuch concentrations enhances corrosion resistance. Additional elements,such as nickel (Ni), manganese (Mn), silicon (Si), carbon (C) andmolybdenum (Mo), may be added to impart other desirable properties. Ofthe three classes, the austenitic stainless steels have the bestcombination of corrosion resistance, mechanical properties, andweldability, where their corrosion resistance is due at least in part tothe high chromium content and nickel additions. An example of anaustenitic stainless steel is the American Iron and Steel Institute(AISI) number 304 stainless steel, also called “type 304 stainlesssteel”, “304 stainless steel” or merely “type 304”. Specific variants oftype 304 stainless steel, such as 304L (for low carbon) are often usedin naval and related applications.

Stainless steel components are often joined by welding. Consumablefiller metals matching or exceeding the chromium content of the basemetal have proven to be effective in ensuring that the welds exhibitsufficient corrosion resistance. Existing filler material for weldingthe various stainless steel base metals, based on Unified NumberingSystem (UNS) designations include austenitic (UNS Nos. W30810, W30910,W31010, W31610, W31710 and W34710), martensitic (UNS Nos. W41010 andW42010 and ferritic (UNS Nos. S40900 and S43080) formulations. Foraustenitic stainless steels, such as type 304, the chromium content ofthe welding consumable is generally between 18 and 20 percent by weight.

During many welding processes, evaporation and oxidation of chromiumfrom the molten weld pool results in the emission of hexavalent chromiumthat is present in the fumes. In fact, the consumable filler material istypically the major source of welding fumes, sometimes accounting forover 80% of the shielded metal arc welding (SMAW) weld. Accordingly, thepossibility exists for significant generation of hexavalent chromium inthe weld fumes. While there are several valence states of chromium (thecomposition and oxidation state of which depends strongly on the processdetails such as arc voltage, type of filler material, welding currentand the presence of a shielding gas in the welding atmosphere), it isthe hexavalent chromium compounds (Cr VI) that are of particularinterest, as they are suspected of leading to lung cancer and otherhealth problems. The problem of a Cr VI-rich local atmosphere isexacerbated when the welding is conducted in confined and related spaceslacking adequate ventilation. For example, welding onboard a shiptypically involves a manual process using an arc method (such as SMAW ora related electric arc method), which has been shown to generateconsiderable amounts of fume, up to 0.3 g/min or 8 g/kg of deposit.While these hazardous conditions can be somewhat meliorated by adequateventilation, such ventilation can be extremely difficult to implement inmany situations, and alone may not be sufficient if the permissibleexposure limits (PELs) to Cr VI are lowered.

An outgrowth of such significant potential health hazards is that theseand other welding operations have been under increased scrutinyrecently. For example, the U.S. Department of Labor's OccupationalSafety and Health Administration (OSHA) sets PELs on Cr VI. The PEL,which can be based on a time weighted average (TWA), for Cr VI aschromic acid is 100 mg/m³, which is equivalent to 52 mg/m³ as Cr VI.Moreover, there is some indication that the PELs might be revised tomuch lower values. The National Institute of Occupational Safety andHealth (NIOSH) has a recommended exposure limit (REL) advisory for Cr VIof 1 mg/m³. Similarly, the new OSHA PEL, which is a regulatory limit,could be as low as the NIOSH REL. This represents a reduction by afactor of over fifty. Manganese-bearing fumes are also a concern formanganese toxicity, which affects the central nervous system. As withhexavalent chromium, manganese has been the focus of considerable recentattention, where the OSHA PEL has been set at 5 mg/m³, with the NIOSHREL of 1 mg/m³.

Accordingly, there is a need for developing a consumable for weldingaustenitic stainless steel that is chromium- and manganese-free to limitthe generation of dangerous emission of these metals in the weldingfumes.

SUMMARY OF THE INVENTION

This need is met by the present invention, where consumables made fromchromium-free alloys are suitable for use as a weld material foraustenitic stainless steels. According to an aspect of the invention, asubstantially chromium-free welding material is disclosed. The materialincludes up to approximately five percent by weight of palladium (Pd),up to approximately ten percent by weight of molybdenum, betweenapproximately five and twenty five percent by weight copper (Cu) and abalance of nickel with up to five percent non-copper alloyingingredients. In one specific composition, a nickel-based alloy withbetween five and ten percent copper and up to approximately one percentpalladium can be used. In another specific composition, up toapproximately three percent molybdenum can be used.

Optionally, the material is configured as a wire, coated electrode,flux-cored wire or the like. Preferably, at least some of the alloyingingredients are elements, including one or more of carbon, boron,nitrogen, manganese, silicon, tungsten, tantalum, niobium and vanadium.While palladium is beneficial in that it provides resistance tolocalized corrosion and ennobles the corrosion potential of the weldmetal, its relatively high cost would favor low concentrations, such asone percent or lower. Even the addition of only small amounts (forexample, 0.12%) improves the localized corrosion properties ofnickel-copper alloys, especially those alloys with lower copper content.The addition of copper to nickel also improves the corrosion behaviorand ennobles the corrosion potential, and the inventors have determinedthat while a relatively broad range of copper concentrations isbeneficial, concentrations of up to approximately twenty five percent byweight are suitable, with concentrations between approximately five andten percent demonstrating even more corrosion resistance for harshenviornments.

According to another aspect of the present invention, a welding deviceincluding up to approximately five percent by weight of palladium, up toapproximately ten percent by weight of molybdenum, up to approximatelytwenty five percent by weight copper and a balance of nickel and up tofive percent non-copper alloying elements is disclosed such that thedevice is substantially chromium-free. In one optional form, the devicecomprises a welding consumable. In one embodiment, the device is definedby a weld metal with higher corrosion potential than a stainless steelworkpiece (for example, a type 304 stainless steel), thereby promotingcorrosion resistance in the weld. In one formulation, the device is madeup of approximately five percent copper and up to approximately onepercent palladium. In another formulation, the device is made up ofbetween approximately five and ten percent copper and up toapproximately one percent palladium. In another, it is made up ofapproximately five percent copper and up to approximately three percentmolybdenum.

According to another aspect of the present invention, a nickel alloyhaving a structural configuration adapted for use as a welding electrodeis disclosed. The alloy includes up to ten percent by weight copper, atleast one element selected from the group consisting of molybdenum andtungsten in an amount up to ten percent by weight, at least one elementselected from the group consisting of silicon and manganese in an amountup to three percent by weight, at least one deoxidizing element and upto five percent by weight palladium. Optionally, the total percentage byweight of copper is between approximately five and ten percent.Similarly, the de-oxidizing element is preferably aluminum or titanium.

According to yet another aspect of the present invention, a method ofwelding a stainless steel base material is disclosed. The methodincludes providing a chromium-free welding consumable in one of thecompositions previously described, and welding the base material withthe welding consumable to produce a welded composition. Optionally, themethod produces less than a forty percent dilution of the weld by thebase material. In one form, the base material comprises an austeniticstainless steel, for example, type 304 stainless steel. The weldingconsumable comprises up to one percent palladium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the known galvanic series for seawater;

FIG. 2 shows a Monel®/304L weld with the ends etched;

FIG. 3 graphically shows the effect of copper content and 25% dilutionwith 304L on corrosion potential, breakdown potential and repassivationpotential of as-cast Ni—Cu-304L buttons in aerated 0.1M NaCl accordingto the present invention;

FIG. 4 graphically shows the corrosion potential of Ni-5Cu—X alloys as afunction of dilution in aerated 0.1M NaCl according to the presentinvention;

FIG. 5 graphically shows the breakdown potential of Ni-5Cu—X alloys as afunction of dilution in aerated 0.1M NaCl according to the presentinvention;

FIG. 6 graphically shows the repassivation potential of Ni-5Cu—X alloysas a function of dilution in aerated 0.1M NaCl according to the presentinvention; and

FIG. 7 illustrates a gas tungsten arc welding (GTAW) process.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have determined that chromium-free weldingconsumables made from nickel alloys containing copper, palladium andmolybdenum are suitable for use as a weld metal for type 304 stainlesssteel. Elimination of chromium from the filler metal leads tosignificant reduction of the chromium content in fumes generated whenwelding a type 304 base metal workpiece. The present inventors have alsodetermined that by controlling dilution of the filler metal by the basemetal, these welds also exhibit good weldability by GTAW (formerly knownas tungsten inert gas (TIG) welding). The strength of these welds iscomparable to welds made with standard 308L filler metal, exhibitingsufficient corrosion resistance in dilute chloride solutions, such as0.1M NaCl solutions. The present inventors have also discovered thatunder certain circumstances (for example, more aggressive environments),weld consumables that employ lower concentrations of copper may exhibiteven further improvements over consumables with relatively highquantities of copper.

If a stainless steel (such as type 304 or its low carbon variant) basemetal is to be welded with a filler metal that is different incomposition than the base metal, then the corrosion of the weldedstructure will be controlled by the galvanic interaction between thetwo. Stainless steel exhibits corrosion resistance because of thepresence of a thin chromium-rich oxy-hydroxide surface film, theso-called passive film, which forms spontaneously upon exposure of afresh metal surface to air or aqueous solution. However, stainlesssteel, like other passive metals, is susceptible to localized corrosionin chloride-containing environments. In fact, the corrosion of passivemetals such as stainless steels is often localized in nature, wherelocalized corrosion in the form of pits and crevices will occur above acharacteristic breakdown potential in a given environment. Thus, onedesign criterion for preventing localized corrosion is to require thatthe corrosion potential stay lower than the breakdown potential.Nevertheless, localized corrosion has been shown to propagate atpotentials lower than the breakdown potential. Therefore, a moreconservative design criterion is that the corrosion potential must staybelow a characteristic repassivation potential that is lower than thebreakdown potential.

When two different metals are electrically coupled (as are a weld and abase metal workpiece) and exposed to the same environment, galvanicinteractions will occur. Referring first to FIG. 1, the more active, orless-noble, metal (i.e., the one with the lower corrosion potential inthat environment) will undergo accelerated attack and the more noblemetal will be protected. This galvanic protection is a form of cathodicprotection for the more noble metal, and is the mechanism for thewell-known corrosion protection of a steel substrate by a zinc coatingin a galvanized structure. The materials farther to the right in thefigure are more noble, those farther to the left, less so. The ranges ofpotentials for types 304 and 316 are indicated, while that of thenickel-copper alloys 400 and K-500 are located between the two.

One key aspect in galvanic coupling is the area ratio of the two metals.It can be shown that i_(a), the anodic current density or corrosion rateof the anode or less noble metal, depends upon the ratio of the areas ofthe cathode and anode, A_(c) and A_(a), and the current density at thecathode, i_(c), according to: $\begin{matrix}{i_{a} = {\frac{A_{c}}{A_{a}}i_{c}}} & (1)\end{matrix}$

Thus, if one area is significantly larger than the other, then thegalvanic potential of the couple is pinned at the uncoupled corrosionpotential of the larger metal. For a welded stainless steel structure,the area of the weld metal is much less than the area of the substratebeing welded, which means that the potential of the weld will be set bythe corrosion potential of the stainless steel in the particularenvironment. If the weld metal is less noble than the stainless steel,the galvanic coupling will result in an increase in the potential of theweld. This can result in aggressive attack of the weld if the stainlesssteel corrosion potential is above the breakdown potential of the weld,or if the less noble weld metal does not passivate and dissolvesactively. However, if the weld metal is noble relative to the stainlesssteel, then the galvanic coupling will result in cathodic protection ofthe weld metal by the stainless steel.

The inventors have found that it is possible to use the fundamentalprinciples outlined above to develop design criteria for a new weldmetal for stainless steel. The design criteria are as follows: (1) thebreakdown and repassivation potentials of the weld metal should behigher than the corrosion potential of the stainless steel substrate toprevent localized attack of the weld metal; and (2) if possible, thecorrosion potential of the weld metal should be slightly higher thanthat of the stainless steel substrate so that the weld metal iscathodically protected.

Weldability Tests

To determine the applicability of various welding consumables, theinventors conducted numerous weldability tests of stainless steel withAlloy 400, commonly known under the trade name Monel®, which, as shownin the figure, is galvanically compatible with 304 stainless steel.Monel® contains 31% copper (typical value), and maximum concentrationsof 2.5% iron (Fe), 2% manganese, 0.5% silicon, 0.3% carbon and 0.024%sulfur (S). Monel® has good corrosion, erosion and cavitation resistancein seawater and is widely used in seawater under conditions of high flowvelocity such as propellers, shafts, condenser tubes and heatexchangers. While Monel® has been used to weld Monel® substrates, thepresent inventors are unaware of any attempt to use it to weld stainlesssteel substrates for the purpose of reducing chromium emissions.

Referring next to FIG. 7, a welding configuration for GTAW is shown,where electrode 3 was placed above welding workpiece (also referred toas base material) 1 having weld joint 2 at the edge to be welded.Electrode 3 is brought close to the joint area, where a direct electriccurrent of 150 A at a voltage of 12V is applied to generate an electricarc between base material 1 and electrode 3. Using this setup, weld rods5 were fused and deposited along the notch adjacent the weld joint 2while using an inert gas (for example, argon) from gas nozzle 4surrounding electrode 3 to cover the area to be welded and therebyminimize or eliminate atmospheric influences.

Welds were made using ¼″ 304L base metal and 0.045″ diametercommercially-available ERNiCu-7 (Monel® 60) or standard 308L stainlesssteel filler wire using the GTAW process. The calculated weld metalcomposition for Monel® 60 welds at two different dilutions and thresholdcomposition values for maintaining good weldability are listed, alongwith the compositions of these materials, in Table 1. TABLE 1Composition range of Monel ® filler metal and 304L base metal. 15% 40%Weldability Element Monel ® Dilution Dilution Threshold (wt %) 60 Wire304L SS calculated calculated Value Ni 63.99 8.08 55.60 41.63 unlimitedCu 28.81 — 24.49 17.29 unlimited Fe 0.76 72.10 11.46 29.30 15 Cr — 18.092.71 7.24 6 Mn 3.49 1.24 3.15 2.59 unlimited Ti 1.99 — 1.69 1.19 notreported Si 0.90 0.37 0.82 0.69 1.5 N — 0.06 0.01 0.02 not reported C0.05 0.03 0.05 0.04 0.4 Others 0.01 0.03 0.01 0.02

Also shown in Table 1 are the calculated values of weld metalcomposition for 15 and 40% dilution for the 304L base metal and Monel®60 filler metal. This represents a typical range for most arc weldingprocesses. In the present context, “dilution” is defined as dilution ofthe filler metal by the base metal. The threshold composition valuesgiven in the last column of the table suggest that the weld dilutionshould be kept below 40% to avoid solidification cracking. GTAW was thewelding process used in this test because it is easier to automate andcontrol than the most common process for manual welding of stainlesssteel, SMAW. Details of the GTAW process are given in Table 2. TABLE 2Details of GTAW procedure Current 150 Amp Voltage 12 V Travel speed 5in/min Heat input 21.6 kJ/in (0.85 kJ/mm) Wire feed speed 45 in/minShielding gas Argon + 5% H₂ Shielding gas flow rate 30 cubic ft/minJoint design V- groove 90°, gap: 0.118 in

Referring next to FIG. 2, an example of a weld achieved with a Monel®60-based consumable is shown. As described below, the 304/Monel® 60 weldstructure exhibited good corrosion resistance to dilute chloridesolutions, but was susceptibile to attack in the copper-richinterdendritic region of the weld structure. Solidification cracks wereobserved in high-dilution welds, but not if the dilution of the Monel®60 filler metal by the 304L base metal was kept below about 30%. Thus,the present inventors are of the belief that avoidance of solidificationcracks with a Monel® 60 filler metal on a 304 stainless steel substrateis possible if the dilution level is kept to no more than 30 to 40%.

While the use of pure argon gas for shielding resulted in surfacecontamination (slagging) and welds of unsatisfactory quality, theinventors discovered that use of an argon environment with 5% hydrogenshielding gas, in conjunction with control of weld heat input,significantly diminished this slagging effect. The inventors alsonoticed that the effect of slagging in the pure argon environment wasworse at high heat inputs, possibly due to the presence of titanium inthe Monel® 60 weld wire. The weld was found to be fully austenitic withperhaps some second phase formation in the interdendritic regions.Compositional profiles determined by scanning electron microscopy andenergy dispersive spectrometer (SEM/EDS) from the base metal into theweld nugget of a particular Monel®/304L weld indicated that there wasabout 10% iron and a few percent of chromium in the weld nugget as aresult of dilution. Also evident was a transition zone in which thecomposition changed from the base metal to the weld metal.

Mechanical Properties and Corrosion Testing

A Monel® 60/304L weld was tested by bending over a ¾″ mandrel, resultingin 15% tensile strain in the outer fibers. The sample passed this testwith no evidence of cracking. Microhardness profiling was performedalong the weld cross-section. The hardness of the Monel® 60 weld metalis slightly below that of welds made with 308L filler metal. Transverseweld tensile tests also exhibited good weld ductility with tensilestrengths comparable to those achieved in welds made under the sameconditions with 308L filler material applied to a type 304L workpiece.In summary, the mechanical properties of the Monel® 60/304L welds wereacceptable and meet the mechanical property requirements for Type 308Lstainless steel welds.

The long term exposure tests on the Monel® 60/304L welds indicated thatthey have good corrosion resistance to mildly aggressive chloridesolutions open to air. No attack was observed after exposure to 0.1MNaCl. After fifty days in artificial seawater the bottom side of theweld was attacked at the interface of the weld metal and base metal, butthe top side was unattacked. Purposeful attack of the weld by aggressiveetchants or polarization in chloride solution to high potentialsrevealed that the most susceptible region of the weld is the copper-richinterdendritic microstructure. In other words, the corrosionsusceptibility is greatest at copper-rich segregated zones in thedendritic weld structure. This led the present inventors to undertakeadditional studies to determine if decreasing the copper content of theconsumables would lead to improved corrosion behavior in the weld.

Accordingly, subsequent corrosion studies focused on alloys with coppercontent lower than the nominal 30% associated with Monel®. Corrosiontesting was performed on welded samples and on buttons prepared byelectric-arc melting of pure elemental mixtures. The buttons were testedin the as-cast and annealed conditions. A large matrix of compositionswas tested within the following ranges: 0-45% copper, 0-3% palladium,0-5% molybdenum and 0-67% dilution by 304L. Cyclic potentiodynamicpolarization measurements and long term exposure tests were performed in0.1M NaCl and artificial seawater. The present inventors found thatcompositions with between five and ten percent copper imparted desirablecorrosion resistance properties, even for aggressive environments.

Referring next to FIG. 3, the effects of copper content and 25% dilutionare shown for as-cast nickel-copper alloys tested in 0.1M NaCl. Threecharacteristic potentials are provided for each condition: E_(CORR),which is the corrosion or open circuit potential, E_(B,100), which isthe breakdown potential as indicated by the potential at which thecurrent density is 100 μA/cm², and E_(RP), which is the repassivationpotential. For samples with no dilution, all three characteristicpotentials increase as the copper content goes from 0 to 5%, whichrepresents an improvement in performance. There is little difference inE_(CORR) at higher copper contents, but the breakdown and repassivationpotentials decrease when the copper content is above 10%. Both thebreakdown and repassivation potentials are lower in this range of 5-10%copper when the alloy is diluted with 25% 304L. It should be noted thatthe values for 304L in this solution are: E_(CORR)=−144 mV SCE (shown,for example, in FIG. 4), E_(B,100)=291 mV SCE, E_(RP)=−94 mV SCE. Thebreakdown potential is higher than for these nickel-copper alloys, whichreflects a greater intrinsic localized corrosion resistance. However,the E_(RP) values of the alloys are higher than for 304L and theE_(CORR) of both the stainless steel and the nickel-copper alloys arefar below the alloy repassivation potentials. This is a good indicationthat the alloys will not suffer localized corrosion in this environment.This is in line with the good performance of Monel®/304L welds in longterm exposure tests in 0.1M NaCl, and appears to be capable of evenbetter performance than Monel®/304L welds in long term exposure to moresevere environments.

As mentioned above, the best corrosion performance is found with a lowcopper content. The effects of alloying with small amounts of palladiumand molybdenum were also studied. Palladium is of interest because itincreases the resistance to localized corrosion and can ennoble alloys,which is beneficial because of the desire to slightly increasing thecorrosion potential of the weld above that of the base metal. Molybdenumis often added to corrosion-resistant alloys to improve localizedcorrosion behavior. The behavior of Ni-5Cu is compared to that ofNi-5Cu-1Pd, Ni-5Cu-3Mo, and Ni-5Cu-1Pd-3Mo in FIGS. 4 through 6, whichpresent the values of E_(CORR), E_(B,100), and E_(RP) as a function ofweld dilution. Of these, the Ni-5Cu-1Pd alloy exhibited the highestvalues of all three critical potentials, except for the extreme case of50% dilution. In that instance, another of the alloys of the presentinvention, Ni-5Cu-3Mo, exhibited the highest breakdown potential. Whilethe general trend appears to favor low (i.e., approximately five to tenpercent copper concentrations), and one particular composition(Ni-5Cu-1Pd) appeared to demonstrate desirable values for all threecharacteristic potentials, it will be appreciated by those skilled inthe art that the specific composition depends on numerous factors,including intended use, cost, corrosion and embrittlement resistance.

While certain representative embodiments and details have been shown forpurposes of illustrating the invention, it will be apparent to thosepersons skilled in the art that various changes in the methods andapparatus disclosed herein may be made without departing from the scopeof the invention.

1. A substantially chromium-free welding material comprising: up toapproximately five percent by weight of palladium; up to approximatelyten percent by weight of molybdenum; between approximately five percentand approximately twenty five percent by weight copper; and a balance ofnickel and up to five percent non-copper alloying ingredients.
 2. Thewelding material of claim 1, wherein said material is configured as awire.
 3. The welding material of claim 1, wherein said material isconfigured as a coated electrode.
 4. The welding material of claim 1,wherein said material is configured as a flux-cored wire.
 5. The weldingmaterial of claim 1, wherein at least some of said alloying ingredientsare elements.
 6. The welding material of claim 5, wherein said elementscomprise at least one of carbon, boron, nitrogen, manganese, silicon,tungsten, tantalum, niobium and vanadium.
 7. The welding material ofclaim 1, wherein said up to approximately five percent by weight ofpalladium comprises up to approximately one percent by weight palladium.8. The welding material of claim 7, wherein said up to approximately onepercent by weight of palladium comprises up to approximately one half ofone percent by weight palladium.
 9. The welding material of claim 1,wherein said between approximately five percent and twenty five percentby weight of copper comprises between approximately five percent toapproximately ten percent by weight copper.
 10. A welding devicecomprising: up to approximately five percent by weight of palladium; upto approximately ten percent by weight of molybdenum; up toapproximately twenty five percent by weight copper; and a balance ofnickel and up to five percent non-copper alloying elements such thatsaid device is substantially chromium-free.
 11. The welding device ofclaim 10, wherein said device comprises a welding consumable.
 12. Thewelding device of claim 10, wherein said device is defined by a highercorrosion potential than a stainless steel workpiece.
 13. The weldingdevice of claim 10, wherein said device comprises between approximatelyfive percent copper and approximately ten percent copper, and up toapproximately one percent palladium.
 14. The welding device of claim 10,wherein said device comprises up to approximately five percent copperand up to approximately three percent molybdenum.
 15. A nickel alloyhaving a structural configuration adapted for use as a weldingelectrode, said alloy comprising: up to ten percent by weight copper; atleast one element selected from the group consisting of molybdenum andtungsten in an amount up to ten percent by weight; at least one elementselected from the group consisting of silicon and manganese in an amountup to three percent by weight; at least one deoxidizing element; and upto five percent by weight palladium.
 16. The alloy of claim 15, whereinthe total percentage by weight of copper is between approximately fiveand ten percent.
 17. The alloy of claim 15, wherein said de-oxidizingelement comprises aluminum or titanium.
 18. The alloy of claim 15,wherein said at least one element selected from the group consisting ofmolybdenum and tungsten is molybdenum in an amount up to three percentby weight.
 19. A method of welding a stainless steel base material, saidmethod comprising: providing a chromium-free welding consumable; andwelding said base material with said welding consumable to produce awelded composition.
 20. The method of claim 19, wherein said weldingconsumable comprises up to approximately five percent by weight ofpalladium, up to approximately ten percent by weight of molybdenum,between approximately five percent and approximately twenty five percentby weight copper and a balance of non-copper alloying ingredients 21.The method of claim 19, wherein said method produces less than a fortypercent dilution by said base material.
 22. The method of claim 19,wherein said base material comprises an austenitic stainless steel. 23.The method of claim 22, wherein said austenitic stainless steelcomprises type 304 stainless steel.
 24. The method of claim 19, whereinsaid welding consumable comprises up to one percent palladium.